A first series of nitrogen infusion runs of 1.3 GHz single-cell cavities at DESY resulted in an unexpected and severe deterioration observed during the vertical cold test. To investigate the origin of the deterioration, one of the cavities underwent extensive radio-frequency measurements and a temperature- and magnetic field-mapping was performed in collaboration with the Helmholtz-Zentrum Berlin. After combining all results, regions of interests were identified and cut-out of the cavity. Subsequent surface analysis techniques (EBSD, PALS, PIXE, SEM/EDX, SIMS, XPS) were applied in order to identify the microscopic origin of the deterioration and especially the differences between hot and cold spots as well as quench spots. An excess of niobium carbides, reducing the thermal conductivity, was identified as the probable cause for the deterioration, and the size- and density-distributions were observed to be crucial for the resulting performance reduction. The origin for the local ...

中文翻译：

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DESY的氮气注入研发，以腔体切口为例

在DESY进行的1.3 GHz单电池腔的第一批氮气注入运行导致在垂直冷测试期间观察到了意想不到的严重劣化。为了研究恶化的根源，对其中一个腔进行了广泛的射频测量，并与柏林的亥姆霍兹-曾特伦姆合作进行了温度和磁场映射。合并所有结果后，确定了感兴趣的区域并切出了空腔。随后的表面分析技术（EBSD，PALS，PIXE，SEM / EDX，SIMS，XPS）被应用，以识别变质的微观原因，尤其是热点和冷点以及淬火点之间的差异。碳化铌过多，降低了导热系数，被认为是造成这种劣化的原因，并且观察到尺寸和密度分布对于导致性能下降至关重要。当地的起源...